astr="."
bstr=astr.join("hello")
print(bstr)

cstr="python 101 202 303"
dstr=cstr.split(" ")
print(dstr)
print("查找是否存在101:",cstr.find('101'))
print("查找是否存在5:",cstr.find('5'))
print("查找是否存在101:",cstr.index('101'))
ostr="demo.10121"
print("查找是否以demo开头:",ostr.startswith('demo'))
print("查找是否以1为结尾:",ostr.endswith('21'))
gstr="hello world"
kstr=gstr.replace('hello','hello221')
print(kstr)



